17 November 2004
Background/Aims: Whether the postobstructive natriuresis and diuresis is related with an altered regulation of sodium transporters in the kidney was examined. Methods: Male Sprague-Dawley rats underwent either bilateral (BUO) or unilateral obstruction (UUO) of the proximal ureters for 24 h. The expression of Na,K-ATPase, type-3 sodium-hydrogen exchanger (NHE3), type-1 bumetanide-sensitive sodium cotransporter (BSC1), and thiazide-sensitive sodium cotransporter (TSC) proteins was determined in the obstructed kidney by Western blot analysis and immunohistochemistry. Catalytic activity of Na,K-ATPase was also determined. Results: The expression of α1 and β1 subunit proteins and the catalytic activity of Na,K-ATPase were significantly decreased in the obstructed kidney in BUO. The expressions of NHE3, BSC1 and TSC proteins were also significantly decreased. Immunohistochemistry confirmed the downregulation of these sodium transporters in the obstructed kidney. In UUO, the expression of sodium transporters was similarly decreased in the obstructed kidney. Conclusion: The postobstructive natriuresis and diuresis may in part be accounted for by a reduced abundance of sodium transporters in the kidney.